Identify whether each of the following statements refers to a problem caused by a positive externality, a negative externality, imperfect information, imperfect competition, a public good, or none of the above:

a. Society would be better off if more people wore smiley-face T-shirts, which brighten the moods of the people who see them.

b. People pay too much for Lame-brand T-shirts because consumers don’t realize the shirts will fall apart after three weeks.

c. Too few people pitch in to purchase bat houses that attract mosquito-eating bats to their neighborhood. Instead, residents hope to benefit from mosquito eradication efforts paid for by others.

d. People buy too many I ♥ New York T-shirts because the market price doesn’t include the pollution costs of making and shipping the shirts.

e. The only grocery store in a small town charges more than $7 for a quart of orange juice.